LOUISVILLE, Kentucky — The mystery surrounding the theft of five barrels of Wild Turkey whiskey deepened Wednesday as company officials said there were no signs anyone broke into the warehouse where the aging bourbon was stolen.

The heist led authorities to a backyard in Franklin County, where the barrels holding the bourbon — weighing up to 500 pounds each — were recovered behind a shed last week. One man has been arrested, and Franklin County Sheriff Pat Melton said investigators have other suspects.

Tests confirmed the liquid inside the barrels was Wild Turkey bourbon distilled in 2009, said Dave Karraker, a spokesman for Campari America, the U.S. subsidiary of Wild Turkey owner's, Italian-based Gruppo Campari. Authorities said labeling on top of each stolen barrel had been spray-painted over.

The bourbon was slated to become Wild Turkey 101, the brand's flagship product, a blend of barrels typically aged for five to eight years, Karraker said.

Bourbon coming off the still is put in new, charred oak barrels for aging in warehouses, a traditional process that gives the whiskey its distinctive taste and color. The stolen barrels weren't full, due to evaporation — known as the "angel's share — taking a small portion over time.

Wild Turkey has beefed up security across its operations since the theft and is doing a full inventory of its stockpiles of aging whiskey in Kentucky, Karraker said. Wild Turkey's distillery is at Lawrenceburg, which is in a county neighboring Franklin County.